1/* 2 * Written by J.T. Conklin <jtc@netbsd.org>. 3 * Public domain. 4 * Adapted for NetBSD/x86_64 by Frank van der Linden <fvdl@wasabisystems.com> 5 */ 6 7#include "DEFS.h" 8 9ENTRY(bzero) 10 RETGUARD_SETUP(bzero, r11) 11 movq %rsi,%rdx 12 13 cld /* set fill direction forward */ 14 xorq %rax,%rax /* set fill data to 0 */ 15 16 /* 17 * if the string is too short, it's really not worth the overhead 18 * of aligning to word boundaries, etc. So we jump to a plain 19 * unaligned set. 20 */ 21 cmpq $16,%rdx 22 jb L1 23 24 movq %rdi,%rcx /* compute misalignment */ 25 negq %rcx 26 andq $7,%rcx 27 subq %rcx,%rdx 28 rep /* zero until word aligned */ 29 stosb 30 31 movq %rdx,%rcx /* zero by words */ 32 shrq $3,%rcx 33 andq $7,%rdx 34 rep 35 stosq 36 37L1: movq %rdx,%rcx /* zero remainder by bytes */ 38 rep 39 stosb 40 41 RETGUARD_CHECK(bzero, r11) 42 ret 43END_WEAK(bzero) 44